IX. Conclusion.
When the list of the fossil corals of the Australian tertiaries is compared with that of the forms living in the Australian and New- Zealand seas, it becomes evident that none of the recent species are represented in the Cainozoic strata. Of the twenty genera now existing around Australia, out of the immediate vicinity of coral- reefs, only three had species in the Tertiaries. Trochocyathus, Flabellum, and Amphihelia, very world-wide genera, were represented in the tertiary strata by species which were very distinct from those now inhabiting the South- Australian and New-Zealand seas. The species which have been found as fossils, and which still exist in the Chinese, Japanese, and Red Seas, are Flabellum Candeanum, and F. distinctum. The Chinese Placotrochus Candeanus is very closely allied to P. elongatus from the Hamilton tertiaries and Cape Otway, and the Deltocyathus is equally so to a West-Indian recent species. The alliance of the coral faunas of the Australian Tertiaries and of the surrounding coral seas is thus very slight ; and the recent species have not been found in the uppermost of the Tertiaries. There are three species common to the Australian and the European Cainozoic deposits ; so that the alliance of the Australian fossil fauna is as great with the European Cainozoic fauna as it is with that of the corals of the tropical seas to the north-east. There is a well-marked species of the Lower Miocene or Oligocene of Mayence, still living in Port Jackson, but it has not been found in the tertiary deposits close by.
The fossil fauna now under consideration cannot be satisfactorily compared with any others with the view of determining a geological relationship. The bulk of the species are peculiar, and such genera as Conosmilia and Paloeoseris are very characteristic. Their species, as well as the Australian Caryophyllioe, Trochocyathi, and Sphenotrochi, present those anomalies which appear to distinguish the forms of the New-Holland fauna. The presence of the Italian species Conotrochus typus, and of the Tortonese Balanophyllia cylindrica and Deltocyathus italicus, in the Australian Tertiaries is quite in keeping with the well-known dispersion of the Maltese and Bund corals and Echinodermata.
The corals of the Australian Tertiaries are very characteristic. They were not reef-builders, but forms which tenanted the sea-bottom, from low spring-tide mark to the depth where Polyzoa abound. The species of the different beds have so great a general and exact resemblance, that they do not offer evidence of any great biological changes having occurred during the deposition of the whole of the fossiliferous tertiary sediments. It is therefore not consonant with the rules of classificatory geology to subdivide the sediments into such series as Oligocene, Lower, Middle, and Upper Miocene, and Pliocene, which for the most part have very distinct faunas in the European area. The diagnosis of the age of the tertiary deposits by the percentage system cannot as yet be applied to the Australian sedimentary beds, in consequence of the Mollusca not having been sufficiently studied ; and the comparison between the existing Austra-
VOL. XXVI. — PART I. Z
